Refrigerating machine



Dec. 19, 1967 I w TAM REFRIGERATING MACHINE 3 Sheets-Sheet 5 Filed Feb. 23, 1966 [AWE/V701? A 7' TORIVE Y5 Patented Dec. 19, 1967 3,358,459 REFRIGERATING MACHINE William A. Tam, Westmont, 111., assignor to Chicago Bridge & Iron Company, Oak Brook, 11]., a corporation of Illinois Filed Feb. 23, 1966, Ser. No. 529,457 16 Claims. (Cl. 626) This invention relates to machines for refrigeration. More particularly, this invention is concerned with a refrigerating machine which is highly suitable for achieving low temperatures, and particularly cryogenic temperatures.

Although the Stirling cycle was first employed in a hot gas engine to develop power, it in more recent times has been found to be a particularly interesting and practical cycle to employ for refrigeration. In refrigerators based on the Stirling cycle, there is generally employed either a stationary regenerator with a variable cylinder volume, or a movable regenerator with a constant cylinder volume. However, in prior systems where there has been both movement of the regenerator with variable cylinder volume a crank shaft has been used to effect movement. The resulting reciprocating action of the piston relative to the cylinder, and of the regenerator, can be considered to move on a harmonic cycle similar to a sine curve, see United States Patents 3,074,244; 2,856,756 and 2,907,169 for Stirling cycle type engines.

Prior refrigerators operating on the Stirling cycle did not permit adequate time for thermodynamic equilibrium to be reached between the gas and the regenerator so that a reversible process could more closely be achieved. Furthermore, the prior art refrigerating machines operating on the Stirling cycle or modifications of it have generally been costly due to the close tolerances or clearances between parts that have been required.

There is provided accordingly by the subject invention, a novel refrigerating machine characterized by having a chamber, formed by a cylinder and piston, of variable volume with a movable regenerator positioned in said chamber. Such a machine can be operated with high efficiency. This refrigerating machine, furthermore, does not employ a crank shaft and thus avoids the harmonic cycling employed in the prior art refrigerating machines.

More particularly, the refrigerating machine of this invention has a closed chamber of variable volume formed by a piston and cylinder for receiving and discharging gas, a movable regenerator in the chamber, means for effecting essentially non-harmonic reciprocating movement of the piston relative to the cylinder to change the chamber volume from a minimum volume to a maximum volume, and means for efiecting essentially non-harmonic, reciprocating movement of the regenerator in the chamber. Furthermore, the reciprocating movement of the piston relative to the cylinder is most suitably effected at substantially constant velocity. It is also advisable to effect movement of the regenerator in the chamber at substantially constant velocity.

In a more specific embodiment, the refrigerating machine has a piston and cylinder which reciprocate relative to each other, said piston and cylinder defining an enclosed gas-retaining chamber having a gas-permeable regenerator therein, the chamber being of variable volume from a minimum volume to a maximum volume, means comprising an inlet port to supply gas under pressure to said chamber to expand the chamber from minimum volume to maximum volume, by effecting relative displacement of the piston to the cylinder by said gas, means to move the regenerator with movement of the piston and cylinder relative to each other to position the regenerator near one end of said chamber at maximum volume, means to move the regenerator from said one end of the chamber to the other end of the chamber without substantial relative movement of the piston and cylinder while the chamber contains said gas under pressure, means closing the inlet port when the regenerator is at said another end, means compn'sing an outlet port downstream of the regenerator which opens when said regenerator is at said another end of the chamber to release the gas in said chamber through the outlet port to a lower pressure thereby cooling the regenerator as the expanding gas rushes through it and out the outlet port, means for displacing the piston relative to the cylinder, without substantial movement of the regenerator, to reduce the chamber to minimum volume and expel residual cool gas through the regenerator and out the outlet port, and means closing the outlet port and opening the inlet port to supply gas to the chamber to expand it from minimum to maximum volume with commensurate movement of the regenerator followed by repetition of the operating cycles.

Associated with the regenerator is a heat exchanger through which a fluid can be passed for cooling the same during operation of the refrigerating machine.

The invention will be discussed further in conjunction with the attached drawings in which: I FIGURES l to 4 are schematic drawings showing the operation of a single cylinder refrigerating machine of this invention, and the relative location of the piston, cylinder and regenerator at different periods during a full cycle of the machine;

FIGURE 5 is a schematic representation of a two cylinder refrigerating machine having opposed pistons within the contemplation of this invention;

FIGURE 6 is an isometric elevation, partially broken away, of a refrigerating machine of this invention;

FIGURE 7 is a sectional view through the central axis of the refrigerating machine of FIGURE 6;

FIGURE 8 is a sectional view on the line 8-8 of FIGURE 7;

FIGURE 9 is a sectional view on the line 99 of FIGURE 7;

FIGURE 10 is an enlarged vertical section showing in greater detail the structure of the regenerator;

FIGURE 11 is a sectional view taken on the line 11-11 of FIGURE 10;

FIGURE 12 is a sectional view showing the elements of the regenerator structure in spaced relationship;

FIGURE 13 is a sectional view on the line 1313 of FIGURE 9, illustrating the insulating structure surrounding the fluid conduit and a retaining packing gland.

Where suitable, the same numbers will be used to describe the same or similar parts of the refrigerating machine apparatus in the various views of the drawings.

With reference to FIGURES 1 to 4, these drawings illustrate schematically the basic operation of a refrigerating machine provided by this invention. As shown in these figures, there is a movable regenerator which is located in a chamber of variable volume. In FIG. 1, the base 10 supports stationary piston 11 which is surrounded by cylinder 12. Rolling diaphragm seal 13 of fabric construction provides a substantially fluid-tight seal between the cylinder 12 and piston 11. Instead of a rolling fabric seal, a conventional piston ring can be employed for the same purpose. Arms 14 are attached to the cylinder 12 and ten minate in cylinders 15. Cylinders 15, or other suitable means, are advisably adjusted to provide a restraining action against upward movement of cylinder 12 due to gas being fed under pressure to chamber 16. This restraining force serves to transfer work, which otherwise would be performed in the chamber as heat of compression with a resulting temperature increase of the gas in the chamber, and have it act away from the chamber. This work can be recovered to lower the total power requirements of operating the machine. By maintaining the gas in the chamber at a low temperature, i.e. not much higher than the gas in the supply source, a greater efficiency results and the machine can accordingly be used to refrigerate to lower temperatures than would be possible otherwise. Instead of cylinders 15', which can be hydraulic cylinders, other suitable means can be used for this purpose. Chamber 15 of variable volume is formed by the piston 11 and cylinder 12, and in the chamber is located regenerator 17. The regenerator 17 is attached to arm 18 which terminates in actuating cylinder 19 or other suitable means for achieving reciprocal motion of the regenerator in a nonharmonic manner, i.e., other than by use of a crank shaft. Conduit 26, having valve 21, supplies gas under pressure to chamber 16. Conduit 22, having valve 23 therein, serves to conduct gas from chamber 16 to the exterior of the chamber.

At the start of the cycle, as shown in FIG. 1, the cylinder 1?. is at its low point of travel as is the regenerator 17. As a result, the chamber '16 is at minimum volume. At this point, gas under pressure, such as 50 to 1500 p.s'.i., is fed by conduit 20 with valve 21 open into chamber 16. While this is being done, valve 23 in conduit 22 is closed, and actuating cylinders 15 are set to provide a significant restraining force against upward displacement of cylinder 12. Thus, if the gas under pressure is at 100 p.s.i., the cylinder 15 can be set to restrain movement of cylinder 12 until the pressure in chamber 16 reaches a predetermined level such as 50 to 75 p.s.i. This restraining action keeps the temperature of the gas expanding the chamber 16 from increasing much above the temperature of the gas as fed into the chamber. The gas filling the chamber increases in pressure approaching the pressure of the gas supply. A good part of the work which would otherwise result from such chamber expansion is, because of the restraining action of cylinder 15 transferred to it and the hydraulic fluid or other means used rather than chamber 16. This greatly increases the ethciency of the machine. As the incoming gas is fed through conduit 20, it forces cylinder 12 upwardly until it reaches maximum upward displacement and chamber 16 reaches maximum volume. As the cylinder 12 is displaced upwardly, regenerator 17 is also moved upwardly and desirably at the same speed at which the cylinder is moved. FIG. 2 illustrates the location of the cylinder and regenerator 17 to its lower-most point in chamber 16. Valve 23 and the regenerator. Once this has been achieved, actuating cylinder 19, which actuates arm 18, lowers regenerator 17 to its lowermost point in chamber 16. Valve 23 "is closed during movement of regenerator 17 from the position shown in FIG. 2 to the position shown in FIG. 3, although valve 21 in conduit 20 can be either open or closed.

Rcgenerator 17 can be of any suitable material but should be gas-permeable so that it can move quite readily in the chamber without creating a significant differential pressure on either side of it during such movement. In addition, although the regenerator is not shown in the drawings of FIGS. 1 to 4 to extend to the cylinder wall, it should in practice do so for highest efficiency.

Before or after regenerator .17 has been moved downward in a reciprocal manner to the posit-ion shown in FIG. 3, valve '21'is closed and valve 23 is opened. Since the gas in chamber 16 is under pressure, opening valve .23 permits exhaust of gas from chamber .16 to an external lower pressure except for the residual .gas which remains in the chamber at such external pressure. In expanding from chamber .16, the gas cools regenerator 17 and brings it to a lower temperature. The refrigerating action is used to advantage by circulating a suitable fluid through the regenerator 17 by means of a heat exchanger, not shown in FIGS. 1 104, although it would be present for refrigerating purposes. After chamber 16 in FIG. 3 has had the gas exhausted by letting it expand outward through conduit 22, the cylinders 15 are actuated to move arms 14 connected to cylinder 12 downwardly, thereby displacing the is reduced to a minimum volume, and the residual cooled gas therein is forced through regenerator 17 thereby cooling it further before it is expelled through conduit 22.

The refrigerating machine of this invention, such as described with reference to FIGS. 1 to 4, is characterized by a movable regenerator and a variable volume chamber 16. In addition, reciprocal movement of the cylinder relative to the piston is effected at a substantially constant velocity since no crank shaft is employed to effect movement. In addition, the regenerator is moved at substantial- 1y constant velocity since it, too, is operated without utilizing a crank shaft. It is realized when movement of the piston and/or the cylinder relative to each other is initiated, that inertia has to be overcome before constant velocity is reached. However, except for initiating each reciprocal action back and forth, the movement is at a substantially constant speed or velocity. This is equally applicable to movement of the regenerator. It is also a feature of this invention to effect movement of the cylinder relative to the piston by means of a gas under substantially constant pressure as the chamber is expanded from minimum volume to maximum volume. In addition, although FIGS. 1 to 4 illustrate a refrigerating machine in which the cylinder moves and the piston .is stationary, it is equally suitable to hold the cylinder stationary and move the piston. Thus, the cylinder and piston need only be made to reciprocate relative to each other in order to utilize the principles of this refrigerating machine.

FIG. 5 of the drawings illustrates a two cylinder refrigerating machine according to this invention in which the cylinders and pistons are positioned in opposing rela-' tionship. Lower base 30 and upper base 31 are positioned in spaced-apart relationship by means of tic-rods 32. Lower piston 33 is mounted on base 30, and upper piston 34 is mounted on base '31. Cylinder 35 is tubular and is positioned to reciprocate up and down. The cylinder interior is divided by means of plate 36, thereby forming chamber 37 on the bottom side, and chamber 38 on the top side, of the cylinder dividing plat-e These chambers are made gas 'tight by means of rolling diaphragm seals 39 connecting the piston and cylinder wa-lis. Actuating cylinders 40 connect with arms 41 to restrain movement of cylinder 35' when a respective chamber is being enlarged by the gas being supplied thereto under pressure. Regenerator 42 is positioned in chamber '37, and it is actuated by arm '43 movab'ly connected to actuating cylinder 44. Similarly, regenerator '45 in chamber 38 is connected to arm '46, which is movab'ly actuated by cylinder 47. Gas is fed under pressure by conduit 48 through valve 49 to chamber '37, and it is removed from chamber 37 by con duit 50 through valve 51. Similarly, gas is fed under pres sure by conduit 52 through valve 53 to chamber 38 and V out of said chamber by conduit 54 through valve 55.

In operating the refrigerating machine of FIG. 5,,gas under pressure is fed through conduit '48 with valve 49 open to chamber 37. with valve 51 closed. This causes cylinder '35 to move upwardly and to expand chamber 37 to maximum volume. Cylinder 40 and arm 41 advisably partially restrain movement of cylinder '35 upwardly so as to keep the gas in chamber 37 from doing uneeessary work in the chamber and thereby increasing unduly in temperature. When cylinder 40 is a hydraulic cylinder, the pressure of the gas expanding the chamber is converted into hydraulic pressure energy cylinder 40. 'Although such restraining action is not essential to operation of the machine, higher efiic'iency and better refrigeration result when .it is employed. Simultaneously, regenerator 42 .is caused to move upwardly with movement of the cylinder 35. contemporaneously with upward movement of cylinder 35., regenerator 45 'in chamber 38 is moved upwardly by means of actuating cylinder 47 and arm 46. Gas in chamber 38 is expelled by such movement through conduit 54 with valve 55 open and valve '53 closed. After the cylinder 35 has reached its upper limit of displacement, valve 49 is closed, and regenerator 42 is caused to move downward by actuating cylinder 44 and arm 43. Valve 51 is then opened and the gas under pressure in chamber 37 exhausted by pressure let-down through conduit 50, thereby causing regenerator 42 to be cooled due to the gas expansion. Cylinder is then displaced downwardly to its low position by means of gas under pressure being fed by conduit 52 through valve 53 to chamber 38. Cylinders 40 and arms 41 are adjusted to partially restrain movement of cylinder 35 to minimize work in chamber 38, thereby keeping the gas from increasing excessively in temperature during expansion of the chamber. As cylinder 35 moves downwardly, regenerator 45 is caused to move downwardly by actuating cylinder 47 and arm 46 until it reaches maximum downward displacement. Then valve 53 is closed, regenerator 45 is moved upwardly to its upper limit, valve 49 is opened and valve 51 closed to permit gas under pressure to enter chamber 37, and valve 55 is opened so that gas under pressure in chamber 38 can be exhausted through conduit 54, thereby causing regenerator 45 to be cooled. The operation of the machine as described can be effected by operating the valves and actuating cylinders manually. However, for rapid operation of the machine, an automatic control system would be employed.

FIGS. 6 to 13 illustrate a specific embodiment of a refrigerating machine of this invention. More specifically, these drawings illustrate a machine having two opposing pistons and a movable H-type cylinder, such as the machine of FIG. 5. For purposes of convenience, only the lower half of the machine is shown in detail in FIGS. 6 and 7, it being understood that a similar pistoncylinder-regenerator arrangement is located above the apparatus of these figures to complete the machine. How

ever, the machine could be readily built as a single cylinder-single piston unit employing only the apparatus shown in FIGS. 6 and 7 and operated in the manner shown by the schematic drawings of FIGURES 1 to 4.

With reference to FIGS. 6 and 7, a platform 60 is supported by legs 61. Circular base plate 62 is mounted on the platform 60. Extending vertically upward from the base 62 and platform 60 are tie rods 63 which connect with an upper base similar to base 62. The tie rods 63 keep the two base portions spaced apart in a rigid manner.

'Mounted between the tie rods is an H-shaped cylinder 64.

seal 69, which is connected circumferentially around the inside of the cylindrical portion 6-8 at the area 70 by bolts 120. The other end of diaphragm 69 is connected at the area 71 around the circular periphery of piston 72 by 'bolts 121. Thearea between the inner walls 67 and 68 of the cylinder and the outer wall 65 is filled with a suitable insulating material 73, such as polyurethane foam.

'- Mounted securely'on base 62 is piston 72. Piston 72 is essentially an elongated, metal tube closed at its upper end by plates 74 and 74a. The bottom end of the piston is partially closed by plates 75 which extend to elongated,

vertical, flat plates 76. The two plates 76 are placed parallel and equidistant from each other, as is shownmore clearly in FIG. 8. The plates 76 are joined, such as by welding to the inside wall of the piston 72, thereby forming corridors 77 and 78. These corridors provide pathways by which gas is conveyed to the chamber space 79 formed by the piston end and the cylinder. Thus, gas

under pressure, such as at about to 1500 p.s.i., can be conveyed through inlet 80 and through corridor 78 to three-way ball valve 82 by means of an opening 83 in the plate 76, or other suitable control device. The gas is then conveyed out of opening 84 which communicates with the chamber 79. In exhausting chamber 79, the valve 82 is manipulated to close inlet 83 and open outlet 85. The gas is then conveyed from the chamber 79 through opening 84, through outlet 85, down corridor 77, and out exit port 81. The inlet port 80 and the outlet port 81 can be made the same size or dilferent sizes, as warranted. Valve 82 is manipulated to open and close the inlet and outlets 83 and 85 by means of a rack and pinion arrangement 86. The rack is caused to move horizontally back and forth by the actuating cylinders 87 to which a fluid under pressure is conveyed by lines 88. The operation of valve 82 is, of course, synchronized to be open and closed as required for operation of the machine. The synchronization can be efiected manually or by automatic control means.

Positioned in chamber 79 is regenerator 90. The movement of the regenerator in the chamber is arranged to be independent of movement of the cylinder 64. With reference to FIGS. 10 and 11 particularly, regenerator 90 has an upper plate 91 and a lower plate 92, each of which is similarly constructed and contain elongated, parallel slots 93. Positioned between the plates 91 and 92 are alternating layers of copper screen 94 and glass cloth 95, or other suitable heat storage material. Included with the regenerator is heat exchange coil 96 which has an inlet conduit 97 and an outlet conduit 98. Spacers 99 serve to keep the plates 91 and 92 apart when the elements of the regenerator, including the layers of copper screen 94 and the glass cloth 95, plus the heat exchange coil 96, are fastened together, such as by bolts 101.

Tubular insulation is placed around lines 97 and 98. This insulation is comprised of an outer tube of rigid plastic reinforced with glass fibers 102 and aninside tube of polyurethane 103 or other suitable insulation, as shown in FIGS. 12 and 13. The conduits 97 and 98 for circulating fluid through the heat exchange coil 96 run through the polyurethane insulated tube 103. Plate 92 is secured to the tubes 102 by means of suitable means, such as an epoxy cement fillet 104. The tubes 102, although they can be of other suitable material, pass through the piston head plate 74 in a slidable arrangement. To prevent gas leak, a packing gland arrangement 105 (FIG. 13) is provided around the tubes 102. A packing 106, such as of polytetraiiuoroethylene, serves to prevent leakage While yet providing for slidable movement of'the tube 102 through the opening 107 in plate 74. The position of the packing gland 165 below plate 74 should also be noted in connection with FIG. 9.

As shown in FIG. 7, the two tubular elements 182 extend from the regenerator to bar 108 which holds the tubes 102 in spaced-apart fixed relationship. The ends of bar 108 are supplied with clamp means 103, as shown in FIG. 8, to removably hold the two tubes 102 at their ends. Rod 3.09 is secured to the bar 108 and projects downwardly until it extends beyond the 'lower end of the piston complex. -To secure rod 109 in position against lateral movement but to permit vertical reciprocal action, bar 110 is fixedly secured to the inside walls of the two plates 76. To bar 110 is secured guide tube 111 through which the rod 109 can slidably move. By actuating rod 109 in a vertical reciprocalmanner, there "is achieved vertical reciprocal movement of the regenerator 90, as well as the heat exchange coil 96 associated therewith. The rod 109 can be moved manually as required or it can be integrated into an automatic system for synchronized movement with movement of the cylinder in an appropriate manner according to whether gas is being fed to the chamber '79 or is being expelled therefrom.

The working end of the piston is closed by three plate segments, two of which 74a serve to block olf the ends of corridors 77 and 78 and the other of which 74 blocks 'the area between the two plates 76 and the cylinder wall.

This central plate 74 has peripheral flanges, thus giving it a dish-type structure, and it is accordingly positioned between the two plates 76 and the piston wall in order 7 to block off that portion of the piston working end. By securing that plate in a removable manner, ready access to the inside of the piston can be obtained such as if it is advisable to do any adjusting of valve 82.

Rod 109, which actuates movement of the regenerator 90, is connected to actuating cylinder 122 to effect movement thereof. Movement of cylinder 64 is partially restrained by the arms 120 which are connected to actuating cylinders 121. The power from this restraining action, if desired, can be recovered to reduce the total power requirement for operating the machine. Thus, by making cylinders 121 hydraulic cylinders, the expanding energy of the gas in chamber 79 can be largely converted to hydraulic pressure energy. The hydraulic fluid can be pumped from a low pressure accumulator to a high pressure accumulator. Useful work may be recovered during the blow down from the high pressure accumulator to the low pressure accumulator. This can be done by passing the hydraulic liquid through a hydraulic motor or turbine.

To seal the rolling diaphragm 69 to the inside of the cylinder and to the outside of the piston, suitable sealing rings can be used in conjunction with bolts to effect a gas-tight seal. However, if it is advisable, the rolling diaphragm can be replaced by a conventional piston ring seal. There are advantages, however, to employing the rolling diaphragm. Among these advantages is the elimination of close tolerances for the piston and cylinder. This efiects a considerable cost reduction and accordingly is the preferred structure.

The lower ends of tubes 97 and 98 which feed fluid to and from the heat exchange coil 95 project out below the bottom of the piston and at such location are made of a flexible material so that they can flex up and down due to displacement of the regenerator in the chamber 79. A moderate tension, however, is maintained on the tubes 97 and 98 by means of springs 123 attached to the tubes and secured at the lower end to brackets 124 located on the bottom of the piston.

The operation of the machine as described in FIGS. 6 to 13 is similar to the operations already described regarding FIGS. '1 to 5. Thus, with reference to FIGS. 6 and 7, :gas under pressure .is fed through port 80, through corridor 78, through inlet 83 to valve 82, and from there it is directed into chamber 79. The gas pressure, with or without restraint by the actuating cylinder 121 and connecting arms 12!), raises the cylinder 64. Simultaneously, the arm 109 is actuated to raise .the regenerator 90. Once the cylinder and the regenerator have reached their uppermost position, the regenerator 90 is lowered by means of arm 169 until it is approximately adjacent the :top of the piston. Then, valve 82 is actuated to close inlet 83 and open outlet 85. As a result, the gas under pressure in chamber 79 is exhausted through outlet 85 through cornidor 77 and out port 81. Then, the cylinder 64 is lowered to expel residual gas in the chamber 79. By the expansion of the gas under pressure from chamber 79, through the regenerator 90, cooling effected which serves to cool the heat exchange coil 96 which in turn cools .21 fluid being circulated therethrough by means of tubes .97 and 9.8. The cycle is then repeated to effect further cooling. Of course, while the described operation is taking place in the lowermost cylinder, the upper most cylinder is also functioning in cooperation with the top piston to effect cooling in the same manner.

The refrigerating machine of this invention has characteristics not previously found in other machines. Among these are the independent timing of each operation or section of the cycle with respect to the other operations. Thus, enlargement of the chamber by the gas fed thereto can :beregulated to take place during any period of time considered suitable. Movement of the regenerator and exhaustion of the gas can also be timed as desired irrespective of .the timing of the chamber expanding operation. The machine also has an infinite turndown ratio.

In addition, the machine permits scheduling of mechanical and thermodynamic events in a sequence independen of each other. Various changes and modifications of the invention can be made and, to the extent that such variations incorporate the spirit of this invention, they are intended to be included within the scope of the appended claims.

What is claimed is: 1. A refrigerating machine having a piston and cylinder which reciprocate relative to each other,

said piston and cylinder defining an enclosed gas-retaining chamber having a gas-permeable regenerator therein, the chamber being of variable volume from a minimum volume to a maximum volume, reans comprising an inlet port to supply gas under pressure to said chamber to expand the chamber from minimum volume to maximum volume by effecting relative displacement of the piston to the cylinder by said gas, 7 means to move the regenerator with movement of the piston and cylinder relative to each other to position the regenerator near one end of said chamber at maximum volume, means to move the regenerator from said one end of the chamber toward the other end of the chamber without substantial relative movement of the piston and cylinder while the chamber contains said gas under pressure, means closing the inlet port when the regenerator is at said other end, means comprising an outlet port downstream of the regenerator which opens when said regenerator is at said other end of the chamber to release the gas in said chamber through the Outlet port to a lower pres sure thereby cooling the regenerator as the expanding gas rushes through it and out the outlet port, means for displacing the piston relative to the cylinder, without substantial movement of the regenerator, to reduce the chamber to minimum volume and expel residual cool gas through the regenerator and out the outlet port, and means closing the outlet port and opening the inlet port to supply gas to the chamber to expand it tram, minimum to maximum volume followed by repetition of the operating cycles. 2. A refrigerating machine having a piston and cylinder which reciprocate relative to each other,

said piston and cylinder defining an enclosed gas-retain ing chamber having a gas-permeable negenerator therein, the chamber being of variable volume from a minimum volume to a maximum volume, means comprising an inlet polt to supply gas under pressure to said chamber to expand the chamber from minimum volume to maximum volume by effecting relative dis lacement of the piston to the cylinder by said gas at substantially constant v locity, means to move the rcgenerator at substantially .con-

stant velocity approximately simultaneouly with movement of the piston and cylinder relative .to each other to position the regenerator near one end of said chamber at maximum volume, means to move the regenerat-or at substantially constant velocity from said one end of the chamber toward the other end .of the chamber without substan-. tial relative movement of the piston and cylinder while the chamber contains said gas under pressure, means closing the inlet port when the regencrator-is at said other end, Y v means comprising an outlet port downstream of the regenerator which opens when said regenerator 'is at said other end of the chamber to release the gas in said chamber through the outlet port to a lower pressure thereby cooling the regenerator as the expanding gas rushes through it and out the outlet port,

means for displacing the piston relative to the cylinder, without substantial movement of the regenerator, to reduce the chamber to minimum volume and expel residue cool gas through the regenerator and out the outlet port, and

means closing the outlet port and opening the inlet port to supply gas to the chamber to expand it from minimum to maximum volume followed by repetition of the operating cycles.

3. The refrigerating machine according to claim 1 in which the regenerator has heat exchange surface means for circulating a fluid therethrough to cool the fiuid.

4. Tte refrigerating machine according to claim 1 in which the chamber is sealed against gas leakage by a rolling flexible diaphragm between the cylinder interior and the piston wall.

5. The refrigerating machine of claim 1 in which the piston has passage means for delivering gas to and from the chamber.

6. The refrigerating machine of claim 2 in which the piston has inlet passage means for delivering gas under pressure from an exterior supply to the chamber and outlet passage means for delivering gas from the chamber under reduced pressure, and valve control means for blocking the outlet passage when gas is being delivered to the chamber and for blocking the inlet passage when gas is being expelled from the chamber.

7. The refrigerating machine of claim 3 in which the heat exchange surface means includes a coil, and a delivery line and a return line are positioned in the piston and extend out therefrom for circulating fluid from an external source through the coil.

8. The refrigerating machine of claim 2 in which the piston is stationary and the cylinder and regenerator reciprocate independently in response to position control actuating means.

9. The refrigerating machine of claim 1 having independent external hydraulic means for moving the regenerator in the chamber, and for moving the piston and cylinder relative to each other.

10. The refrigerating machine of claim 1 in which the regenerator is connected to an actuating member extending out of, and operable from outside, the chamber to move the regenerator back and forth.

11. The refrigerating machine of claim 6 in which the valve is a three-way valve positioned at the piston end adjacent the chamber.

12. A refrigerating machine having two opposed pistons in an H-shaped cylinder which reciprocates relative to the pistons,

each piston and the cylinder defining an enclosed gasretaining chamber having a gas-permeable regenerator therein,

each chamber being of variable volume from a minimum volume to a maximum volume, with one of said chambers being at minimum volume when the other chamber is at maximum volume.

means comprising an inlet port to supply gas under pressure to each chamber to expand the chamber from minimum volume to maximum volume by effecting relative displacement of the cylinder to the piston by said gas,

means to move the regenerator with movement of the piston and cylinder relative to each other to position the regenerator near one end of each chamber at maximum volume,

means to move the regenerator at substantially constant velocity from said one end of each chamber toward the other end of the chamber without significant movement of the piston and cylinder while the chamber contains said gas under pressure,

means closing the inlet port when the regenerator is at said other end, means comprising an outlet port downstream of the regenerator which opens when said regenerator is at said other end of the chamber to release the gas in said chamber through the outlet port to a lower pressure thereby cooling the regenerator as the expanding gas rushes through it and out the outlet port,

means for displacing the cylinder relative to the piston, Without substantial movement of the regenerator in the chamber, to reduce the chamber to minimum volume and expel residual cool gas through the regenerator and outlet port, and

means closing the outlet port and opening the inlet port to supply gas to each chamber to expand it from minimum to maximum volume followed by repetition of the operating cycles.

13. A refrigerating machine having a closed chamber of variable volume formed by a piston and cylinder for receiving and discharging gas, a movable regenerator in the chamber, means for effecting essentially nonharmonic reciprocating movement of the piston relative to the cylinder to change the chamber volume from a minimum volume to a maximum volume, and means for effecting essentially non-harmonic reciprocating movement of the regenerator in the chamber independent of movement of the piston.

14. A refrigerating machine according to claim 13 in which reciprocating movement of the piston relative to the cylinder is effected by the means at substantially constant velocity, and movement of the regenerator is eifected by the means at substantially constant velocity.

15. A refrigerating machine according to claim I having means to partially restrain movement of the cylinder relative to the piston when the chamber is being enlarged from minimum to maximum volume by gas supplied thereto under pressure.

16. A refrigerating machine according to claim 15 in which power from the restraining means is recovered to reduce the total power requirement for operating the machine.

References Cited UNITED STATES PATENTS 3,091,092 5/1963 Dros 626 3,188,818 6/1965 Hoyan 62--6 3,218,815 11/1965 Chellis 626 3,274,786 9/1966 Hoyan 626 WILLIAM J. WYE, Primary Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3,358',4'59 December 19 1967 William A. Tam

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 45, for "17 to its lowermost point in chamber 16 V lve 23" read at the upward peak of movement of the cylinder column 9, line 6, for "residue" read residual line 15, for "Tte" read The column 10, lines 58 and 60, for "Hoyan", each occurrence, read Hogan Signed and sealed this 14th day of January 1969.

(SEAL) Attest: Edward M. Fletcher, Jr. EDWARD J. BRENNER Attesting Officer Commissioner of Patents 

1. A REFRIGERATING MACHINE HAVING A PISTON AND CYLINDER WHICH RECIPROCATE RELATIVE TO EACH OTHER, SAID PISTON AND CYLINDER DEFINING AN ENCLOSED GAS-RETAINING CHAMBER HAVING A GAS-PERMEABLE REGENERATOR THEREIN, THE CHAMBER BEING OF VARIABLE VOLUME FROM A MINIMUM VOLUME TO A MAXIMUM VOLUME, MEANS COMPRISING AN INLET PORT TO SUPPLY GAS UNDER PRESSURE TO SAID CHAMBER TO EXPAND THE CHAMBER FROM MINIMUM VOLUME TO MAXIMUM VOLUME BY EFFECTING RELATIVE DISPLACEMENT OF THE PISTON TO THE CYLINDER BY SAID GAS, MEANS TO MOVE THE REGENERATOR WITH MOVEMENT OF THE PISTON AND CYLINDER RELATIVE TO EACH OTHER TO POSITION THE REGENERATOR NEAR ONE END OF SAID CHAMBER AT MAXIMUM VOLUME, MEANS TO MOVE THE REGENERATOR FROM SAID ONE END OF THE CHAMBER TOWARD THE OTHER END OF THE CHAMBER WITHOUT SUBSTANTIAL RELATIVE MOVEMENT OF THE PISTON AND CYLINDER WHILE THE CHAMBER CONTAINS SAID GAS UNDER PRESSURE, MEANS CLOSING THE INLET PORT WHEN THE REGENERATOR IS AT SAID OTHER END, MEANS COMPRISING AN OUTLET PORT DOWNSTREAM OF THE REGENERATOR WHICH OPENS WHEN SAID REGENERATOR IS AT SAID OTHER END OF THE CHAMBER TO RELEASE THE GAS IN SAID CHAMBER THROUGH THE OUTLET PORT TO A LOWER PRESSURE THEREBY COOLING THE REGENERATOR AS THE EXPANDING GAS RUSHES THROUGH IT AND OUT THE OUTLET PORT, MEANS FOR DISPLACING THE PISTON RELATIVE TO THE CYLINDER, WITHOUT SUBSTANTIAL MOVEMENT OF THE REGENERATOR, TO REDUCE THE CHAMBER TO MINIMUM VOLUME AND EXPEL RESIDUAL COOL GAS THROUGH THE REGENERATOR AND OUT THE OUTLET PORT, AND MEANS CLOSING THE OUTLET PORT AND OPENING THE INLET PORT TO SUPPLY GAS TO THE CHAMBER TO EXPAND IT FROM MINIMUM TO MAXIMUM VOLUME FOLLOWED BY REPETITION OF THE OPERATING CYCLES. 